Antimicrobial composition having efficacy against endospores

ABSTRACT

A sporicidal composition has a moderately low pH and includes at least one oxidizing acid and the dissociation product of at least one inorganic oxidizing agent. Very high effective solute concentrations can enhance the efficacy of the composition. Embodiments of the composition can be applied to a surface and allowed to absorb into the endospore, ultimately killing at least some of those bacteria in mature endospore form. The surface being treated can be an inanimate surface, particularly a hard surface, or a medical device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/745,094, which issued as U.S. Pat. No. 10,827,750 on 10 Nov. 2020,which is a national stage entry of international appl. no.PCT/US2016/042780, filed 18 Jul. 2016, which claims the benefit of U.S.provisional patent application Nos. 62/194,141 and 62/194,210, filed 17Jul. 2015 and 18 Jul. 2015, respectively, the disclosures of which areincorporated herein by reference.

BACKGROUND INFORMATION

Unlike a true spore, an endospore is not an offspring of another livingorganism. Nevertheless, the terms “spore” and “endospore” are usedinterchangeably hereinthroughout.

A vegetative bacterium is one which can grow, feed and reproduce. Whennutrients become scarce, certain vegetative bacteria begin a processreferred to as “sporulation,” where they take on a reduced, dormant formwhich permits them to survive without nutrients and gives themresistance to UV radiation, desiccation, elevated temperatures, extremefreezing and chemical disinfectants. Soon after environmental conditionsreturn to being favorable for vegetative growth, such bacteria can exittheir dormant state (“spore germination”) with the spore corerehydrating, the cortex hydrolyzing, the coat being shed and,ultimately, DNA replication being initiated. For additional informationon these complex processes, the interested reader is directed to any ofa variety of texts such as, for example, J. C. Pommerville, Fundamentalsof Microbiology, 10th ed. (Jones & Bartlett Learning; Burlington,Mass.).

At the outset of the sporulation step, a vegetative bacterium called a“mother cell” makes a copy of its DNA and then forms a membrane aroundthe new copy of DNA, with the section of the cell having the copied DNAcompletely surrounded by a membrane being referred to as a “forespore.”The next morphological stage of sporulation is “engulfment” of theforespore by its mother cell, a process that is analogous tophagocytosis; when engulfment is complete, the forespore is entirelysurrounded by its inner and outer membranes and free in the mother cellcytoplasm. Around this core of the spore is assembled a series ofprotective structures, completion of which results in a matureendospore, which is released after the mother cell is broken apart.

Endospores have a multi-layer structure, all of which protect thenucleus. The nucleus is protected by a number of layers, set forth belowin Table 1 in order from inside-to-outside:

TABLE 1 Layer Description (1) core protoplast that contains RNA, DNA,dipicolinic acid, low molecular weight basic proteins, and variousminerals such as Ca, K, Mn and P (2) cortical (outer) non-crosslinked orlightly crosslinked peptido- membrane glycan-containing layer thatdevelops into cell wall during germination (3) cortex peptidoglycan andmanuronic acid residues (4) inner spore coat primarily acidicpolypeptides (5) outer spore coat primarily protein with somecarbohydrates and lipids and, in the case of C. difficile, a largeamount of phosphorusThe inner spore coat is soluble in alkali solutions, but the outer sporecoat is resistant to hydrolysis from alkalis, probably due insignificant part to its numerous disulfide (—S—S—) linkages.

Spores are extremely difficult to eradicate and are involved in thespread of diseases such as Clostridium difficile (C. diff) infection andanthrax.

C. difficile is a Gram-positive, spore-forming bacterium often found inhealthcare facilities and is the cause of antibiotic-associateddiarrhea. C. difficile infection is a growing problem, affectinghundreds of thousands of people each year, killing a significant portionof those affected. C. difficile spores are resistant to most routinesurface cleaning methods, remaining viable in the environment for longperiods of time.

Anthrax is an acute, usually lethal, disease that affects both humansand animals, caused by the bacterium Bacillus anthracis (B. anthracis),which spores can be produced in vitro and used as a biological weapon.Anthrax does not spread directly from one infected animal or person toanother, instead being spread by spores.

Sporostatic compounds are not sporicidal, i.e., they do not kill spores;instead, they inhibit germination of spores or cause germinated sporesto grow abnormally. Spores can survive exposure to these compounds andthen grow after sporostatic compounds no longer are present. Sporostaticcompounds include phenols and cresols, organic acids and esters,alcohols, quaternary ammonia compounds, biguanides, and organomercurycompounds. Certain of these sporostatic compounds can be marginallysporicidal at high concentrations; see, e.g., A. D. Russell, “BacterialSpores and Chemical Sporicidal Agents,” Clinical Microbiology Reviews,pp. 99-119 (1990)) for the relative concentrations of certainsporostatic compounds needed to achieve any sporicidal efficacy.

Commonly employed spore treatment options include aldehydes,particularly gluteraldehyde and formaldehyde; chlorine-releasing agentsincluding Cl₂, sodium hypochlorite, calcium hypochlorite, and chlorinereducing agents such as dichloroisocyanurate; iodine and iodophors;peroxygens including hydrogen peroxide and peracetic acid; gases such asethylene oxide, propylene oxide and ozone; and β-propiolactone. Themechanisms of their activities against spores are not particularly wellunderstood although, in all cases, the activity is rate-limited by thepermeation of the active molecule(s) through the protective layers ofthe spore. This need to penetrate the various layers of protection meansthat spores must be exposed to these products for long periods of timeat high concentrations.

U.S. Pat. Nos. 8,940,792 and 9,314,017 as well as U.S. Pat. Publ. Nos.2010/0086576, 2013/0272922, 2013/0079407 and 2016/0073628 describeantimicrobial compositions and various uses therefor. The core andcortex (including cortical membrane) of a spore are susceptible todissolution and lysis by the types of high osmolarity compositionsdescribed in these documents. However, such compositions have not beenfound to be particularly effective against spores, likely due to alimited ability to break down and then penetrate the outer and innerspore coats.

That which remains desirable is a composition that is capable ofpenetrating the various defenses of endospores and killing bacteriatherein. Such a composition preferably is effective against endosporesof bacteria such as of C. difficile and B. anthracis while notpresenting toxicity concerns toward humans who handle or contact it.

SUMMARY

In one aspect is provided a composition that can kill a variety ofendospore-forming bacteria while in mature endospore form. Embodimentsof the composition are effective against the various defenses ofbacteria in endospore form, specifically, disulfide bonds can becleaved, intrinsic hydrophobicity can be overcome, peptidoglycan can bedisrupted, and the core and cortical membrane can be lysed.

The composition is acidic but has a pH≥1.5 and includes solvent andsolute components, the latter including at least one oxidizing acid andthe dissociation product of at least one electrolyte oxidizing agent. Incertain embodiments, the composition also can include one or more of anorganic liquid, a wetting agent (particularly an ionic surfactant), andany of a variety of non-oxidizing electrolytes. Advantageously, thecomposition need not include an active antimicrobial agent to besporicidal.

The composition has an effective solute concentration of at least 1.0Osm/L, typically at least 1.5 Osm/L and often even higher, up to thesolubility limit of the solute component in the solvent component.

Also provided is a method of treating a surface. The method involvesapplying an embodiment of the foregoing composition to the surface andpermitting the composition to be absorbed into the endospore and to killat least some of those bacteria in mature endospore form. The surfacebeing treated can be an inanimate surface, particularly a hard surface,and advantageously a hard surface in a healthcare facility.

Embodiments of the composition, when used in conjunction with tests suchas ASTM standard E2197-11 and AOAC Official Method 966.04 can providepositive (passing) results within commercially relevant timeframes. Forexample, janitorial-type disinfecting treatment of (inanimate) hardsurfaces can be effected in less than 20 minutes, while sterilizingtreatment of medical instruments can be effected in less than 4 hours.

Other aspects of the invention will be apparent to the ordinarilyskilled artisan from the detailed description that follows. To assist inunderstanding that description, certain definitions are providedimmediately below, and these are intended to apply throughout unless thesurrounding text explicitly indicates a contrary intention:

-   -   “comprising” means including, but not be limited to, the listed        ingredients or steps;    -   “consisting of” means including only the listed ingredients (or        steps) and minor amounts of inactive additives or adjuvants;    -   “consisting essentially of” means including only the listed        ingredients (or steps), minor amounts (less than 5%, 4%, 3%, 2%,        1%, 0.5%, 0.25%, or 0.1%) of other ingredients that supplement        sporicidal activity and/or provide a secondary effect (e.g.,        antifogging, soil removal, etc.) that is desirable in view of        the intended end use, and/or inactive additives or adjuvants;    -   “polyacid” means a compound having at least two carboxyl groups        and specifically includes dicarboxylic acids, tricarboxylic        acids, etc.;    -   “pH” means the negative value of the base 10 logarithm of [H+]        as determined by an acceptably reliable measurement method such        as a properly calibrated pH meter, titration curve against a        known standard, or the like;    -   “pK_(a)” means the negative value of the base 10 logarithm of a        particular compound's acid dissociation constant;    -   “E⁰ _(red)” means the standard voltage for a reduction        half-reaction in water at 25° C.;    -   “buffer” means a compound or mixture of compounds having an        ability to maintain the pH of a solution to which it is added        within relatively narrow limits;    -   “buffer precursor” means a compound that, when added to a        mixture containing an acid, results in a buffer;    -   “electrolyte” means a compound that exhibits some dissociation        when added to water;    -   “non-oxidizing electrolyte” means an electrolyte other than one        that can act as an oxidizing agent;    -   “benzalkonium chloride” refers to any compound defined by the        following general formula

where R³ is a C₈-C₁₈ alkyl group, or any mixture of such compounds;

-   -   “effective solute concentration” is a measurement of the        colligative property resulting from the number of moles of        molecules (from nonelectrolyte) or ions (from electrolytes)        present in a given volume solution, often presented in units of        osmoles per liter;    -   “δ_(p)” is the dipolar intermolecular force Hansen Solubility        Parameter (HSP), with the value for a solution or mixture of        solvents being calculated by

$\begin{matrix}{\delta_{p} = {\sum\limits_{i = 1}^{n}\left( {\delta_{di} \times x_{di}} \right)}} & (I)\end{matrix}$where δ_(di) is the energy from dipolar intermolecular force for solventcomponent i, x_(di) is the percentage of solvent component i relative tothe total amount of solvent components, and n is the total number ofsolvent components;

-   -   “oxyacid” means a mineral acid that contains oxygen;    -   “substituted” means containing a heteroatom or functionality        (e.g., hydrocarbyl group) that does not interfere with the        intended purpose of the group in question;    -   “microbe” means any type of microorganism including, but not        limited to, bacteria, viruses, fungi, viroids, prions, and the        like;    -   “antimicrobial agent” means a substance having the ability to        cause greater than a 90% (1 log) reduction in the number of one        or more microbes;    -   “active antimicrobial agent” means an antimicrobial agent that        is effective only or primarily during the active parts of the        lifecycle, e.g., cell division, of a microbe;    -   “germicide” means a substance that is lethal to one or more        types of harmful microorganisms;    -   “disinfectant” means a substance that is lethal to one or more        types of bacteria;    -   “high level disinfectant” means a disinfectant that is capable        of killing all bacteria except for small amounts of bacteria in        endospore form;    -   “sterilant” means a substance capable of eliminating at least a        6 log (99.9999%) reduction of all microbes, regardless of form;    -   “contact time” means the amount of time that a composition is        allowed to contact a surface and/or an endospore on such a        surface;    -   “hard surface” means any surface that is non-porous to fluids        and, in most cases, non-deformable; and    -   “healthcare” means involved in or connected with the maintenance        or restoration of the health of the body or mind.

Throughout this document, unless the surrounding text explicitlyindicates a contrary intention, all values given in the form ofpercentages are w/v, i.e., grams of solute per liter of composition. Therelevant portion(s) of any specifically referenced patent and/orpublished patent application are incorporated herein by reference.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The sporicidal composition is described first in terms of its propertiesand components, many of which are widely available and relativelyinexpensive, and then in terms of certain uses.

The solvent component of the composition typically includes asignificant amount of water. Relative to its overall volume, acomposition often includes up to 20%, 25%, 30%, 33%, 35%, 40%, 45%, 50%,or even 55% (all v/v). On a per liter basis, a composition oftenincludes from ˜50 to ˜500 mL, commonly from ˜75 to ˜475 mL, morecommonly from ˜100 to ˜450 mL, usually from ˜125 to ˜425 mL, typicallyfrom ˜150 to ˜400 mL, and most typically 250±50 mL water. The water neednot be specially treated (e.g., distilled and/or deionized), althoughpreference certainly can be given to water that does not interfere withthe intended antimicrobial effect of the composition.

The solvent component of the composition often includes at least oneorganic liquid, and, in some embodiments, preference is given to thoseorganic liquids with δ_(p) values lower than that of water (δ_(p)˜16.0MPa^(1/2)). Where at least one organic liquid is present in the solventcomponent, the δ_(p) value of the overall solvent component generally isless than 16.0, no more than 15.6, no more than 15.2, no more than 15.0,no more than 14.6 or no more than 14.0 MPa^(1/2). In some embodiments,the δ_(p) value of the overall solvent component can range from 13.1 to15.7 MPa^(1/2), from 13.3 to 15.6 MPa^(1/2), from 13.5 to 15.5MPa^(1/2), and even from 13.7 to 15.4 MPa^(1/2).

The organic liquid(s) often is/are present at concentrations of up to60%, commonly 5 to 50%, more commonly 10 to 45%, even more commonly 15to 40%, and typically 20 to 35% (all w/v, based on total volume ofsolvent component).

The amount of a given organic liquid (or mixture of organic liquids) tobe added to water can be calculated using formula (I) if a targetedδ_(p) value is known. Similarly, a projected δ_(p) value can becalculated using formula (I) if the amount of organic liquid(s) andtheir individual δ_(p) values are known.

The solvent component can consist of, or consist essentially of, onlywater or only one or more organic liquids, with preference being givento mixtures of species of the same genus of organic liquids, e.g., twoethers or two alcohols rather than one ether and one alcohol. In certainpreferred embodiments, the solvent component can consist of, or consistessentially of, water and an organic liquid, preferably one having aδ_(p) value less than 15.5 MPa^(1/2). In yet other embodiments, thesolvent component can consist of, or consist essentially of, water andtwo or more organic liquids, with the resulting solvent component havingδ_(p) value that can be calculated using formula (I); again, preferenceis given to mixtures of species of the same genus of organic liquids,e.g., two ethers or two alcohols rather than one ether and one alcohol.

With respect to organic liquids that can be employed in the solventcomponent, those which are miscible with one another and/or water arepreferred. Non-limiting examples of potentially useful organic liquidsinclude ketones such as acetone, methyl butyl ketone, methyl ethylketone and chloroacetone; acetates such as amyl acetate, ethyl acetateand methyl acetate; (meth)acrylates and derivatives such as acrylamide,lauryl methacrylate and acrylonitrile; aryl compounds such as benzene,chlorobenzene, fluorobenzene, toluene, xylene, aniline and phenol;aliphatic alkanes such as pentane, isopentane, hexane, heptane anddecane; halogenated alkanes such as chloroform, methylene dichloride,chloroethane and tetrachloroethylene; cyclic alkanes such ascyclopentane and cyclohexane; and polyols such as ethylene glycol,diethylene glycol, propylene glycol, hexylene glycol, and glycerol. Whenselecting such organic liquids for use in the solvent component of thecomposition, possible considerations include avoiding those whichcontain a functional group that will react with the acid(s) andoptionally, salt(s) employed in the composition and favoring those whichpossess higher regulatory pre-approval limits.

Preferred organic liquids include ethers and alcohols due to their lowtissue toxicity and environmentally friendliness. These can be added atconcentrations up to the solubility limit of the other ingredients inthe composition.

Ether-based liquids that can be used in the solvent component includethose defined by the following general formulaR¹(CH₂)_(x)O—R²—[O(CH₂)_(z)]_(y)Z   (II)where x is an integer of from 0 to 20 (optionally including, where2≤x≤20, one or more points of ethylenic unsaturation), y is 0 or 1, z isan integer of from 1 to 4, R² is a C₁-C₆ linear or branched alkylenegroup, R¹ is a methyl, isopropyl or phenyl group, and Z is a hydroxyl ormethoxy group. Non-limiting examples of glycol ethers (formula (II)compounds where Z is OH) that can be used in the solvent component areset forth below in Table 2.

TABLE 2 Representative glycol ethers, with formula (II) variables andδ_(p) values ~δ_(p) R¹ x R² y z (MPa^(1/2)) ethylene glycol monomethylether CH₃ 0 (CH₂)₂ 0 — 9.2 ethylene glycol monoethyl ether CH₃ 1 (CH₂)₂0 — 9.2 ethylene glycol monopropyl ether CH₃ 2 (CH₂)₂ 0 — 8.2 ethyleneglycol monoisopropyl ether (CH₃)₂CH 0 (CH₂)₂ 0 — 8.2 ethylene glycolmonobutyl ether CH₃ 3 (CH₂)₂ 0 — 5.1 ethylene glycol monophenyl etherC₆H₅ 0 (CH₂)₂ 0 — 5.7 ethylene glycol monobenzyl ether C₆H₅ 1 (CH₂)₂ 0 —5.9 diethylene glycol monomethyl ether CH₃ 0 (CH₂)₂ 1 2 7.8 diethyleneglycol monoethyl ether (DGME) CH₃ 1 (CH₂)₂ 1 2 9.2 diethylene glycolmono-n-butyl ether CH₃ 3 (CH₂)₂ 1 2 7.0 propylene glycol monobutyl etherCH₃ 3 (CH₂)₃ 0 — 4.5 propylene glycol monoethyl ether CH₃ 1 (CH₂)₃ 0 —6.5 propylene glycol monoisobutyl ether (CH₃)₂CH 1 (CH₂)₃ 0 — 4.7propylene glycol monoisopropyl ether (CH₃)₂CH 0 (CH₂)₃ 0 — 6.1 propyleneglycol monomethyl ether CH₃ 0 CH₂CH(CH₃) 0 — 6.3 propylene glycolmonophenyl ether C₆H₅ 0 CH₂CH(CH₃) 0 — 5.3 propylene glycol monopropylether (PGME) CH₃ 2 CH₂CH(CH₃) 0 — 5.6 triethylene glycol monomethylether CH₃ 0 (CH₂)₂ 2 2 7.6 triethylene glycol monooleyl ether CH₃ 17*(CH₂)₂ 2 2 3.1 *includes unsaturation at the 9 position

Cyclic and C₁-C₁₆ acyclic (both linear and branched, both saturated andunsaturated) alcohols, optionally including one or more points ofethylenic unsaturation and/or one or more heteroatoms other than thealcohol oxygen such as a halogen atom, an amine nitrogen, and the like,can be employed as an organic liquid in the solvent component of thecomposition. Non-limiting examples of representative examples arecompiled in the following table.

TABLE 3 Representative alcohols, with δ_(p) values ~δ_(p) (MPa^(1/2))2-propenol 10.8 1-butanol 5.7 t-butyl alcohol 5.1 4-chlorobenzyl alcohol7.5 cyclohexanol 4.1 2-cyclopentenyl alcohol 7.6 1-decanol 10.02-decanol 10.0 2,3-dichloropropanol 9.2 2-ethyl-1-butanol 4.3 ethanol8.8 2-ethyl-hex anol 3.3 isooctyl alcohol 7.3 octanol 3.3 methanol 12.3oleyl alcohol 2.6 1-pentanol 4.5 2-pentanol 6.4 1-propanol 6.82-propanol (IPA) 6.1

For further information on organic liquid-containing solvent components,the interested reader is directed to U.S. Pat. Publ. No. 2016/0073628.

The composition is acidic, more particularly having a pH of no more than4, and certain embodiments can have a pH of no more than 3.8, 3.7, 3.6,3.5, 3.4, 3.3, 3.2, 3.1, 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3 or even2.2. The composition has a pH of at least 1.5, generally at least 1.75,and typically at least 2.0. Ranges of pH values employing each of thelower limits in combination with each of the upper limits areenvisioned. Embodiments of the composition can have pH values of2.75±1.15, 2.70±1.05, 2.65±1.0, 2.60±0.75, 2.55±0.60, 2.50±0.55 and2.45±0.45.

Acidity can be achieved by adding to the solvent component (or viceversa) one or more acids. Strong (mineral) acids such as HCl, H₂SO₄,H₃PO₄, HNO₃, H₃BO₃, and the like or organic acids, particularly organicpolyacids, may be used. Examples of organic acids include monoproticacids such as formic acid, acetic acid and substituted variants (e.g.,hydroxyacetic acid, chloroacetic acid, dichloroacetic acid, phenylaceticacid, and the like), propanoic acid and substituted variants (e.g.,lactic acid, pyruvic acid, and the like), any of a variety of benzoicacids (e.g., mandelic acid, chloromandelic acid, salicylic acid, and thelike), glucuronic acid, and the like; diprotic acids such as oxalic acidand substituted variants (e.g., oxamic acid), butanedioic acid andsubstituted variants (e.g., malic acid, aspartic acid, tartaric acid,citramalic acid, and the like), pentanedioic acid and substitutedvariants (e.g., glutamic acid, 2-ketoglutaric acid, and the like),hexanedioic acid and substituted variants (e.g., mucic acid),butenedioic acid (both cis and trans isomers), iminodiacetic acid,phthalic acid, and the like; triprotic acids such as citric acid,2-methylpropane-1,2,3-tricarboxylic acid, benzenetricarboxylic acid,nitrilotriacetic acid, and the like; tetraprotic acids such as prehniticacid, pyromellitic acid, and the like; and even higher degree acids(e.g., penta-, hexa-, heptaprotic, etc.). Where a tri-, tetra-, orhigher acid is used, one or more of the carboxyl protons can be replacedby cationic atoms or groups (e.g., alkali metal ions), which can be thesame or different.

Because of the nature of some of the defenses resulting from the variouslayers present in endospores, the composition must include at least oneoxidizing acid. Many oxyacids, such as perchloric, chloric, chlorous,hypochlorous, persulfuric, sulfuric, sulfurous, hyposulfurous,pyrosulfuric, disulfurous, thiosulfurous, pernitric, nitric, nitrous,hyponitrous, perchromic, chromic, dichromic, permanganic, manganic,perphosphoric, phosphoric, phosphorous, hypophosphorus, periodic, iodic,iodous, etc., are considered to be oxidizing acids. Organic oxidizingacids include, but are not limited to, peracetic acid, peroxalic acidand diperoxalic acid.

Preferred oxidizing acids are those which have relatively high pK_(a)values (i.e., are not considered to be particularly strong acids) andpositive standard potentials (E⁰ _(red)). The former permits productionof a composition that has a pH value that is not too low, i.e., below˜1.5, preferably not below ˜1.75, more preferably not below ˜2, and mostpreferably not below ˜2.2, so that the composition can be used withoutextreme protective measures by those charged with handling and applyingthem to surfaces and/or destroying components of articles to be treated.A positive standard potential permits the acid to have sufficientoxidizing capacity to permit overcoming or avoidance of certainendospore defenses such as, for example, oxidation of disulfide linkagesand protein polymers on the endospore coat, which allows the outer sporecoat to be breached.

Preferred pK_(a) values are greater than ˜1, greater than ˜1.5, greaterthan ˜2, greater than ˜2.5, greater than ˜3, greater than ˜3.5, greaterthan ˜4, greater than ˜4.5, greater than ˜5, and even greater than ˜5.5.Acids with lower pK_(a) values can be used if other steps are taken toensure compliance with required or desired properties of the compositionsuch as pH range (discussed above) and effective solute concentration(discussed below).

Preferred E⁰ _(red) values are those which are at least +0.20 V, atleast +0.25 V, at least +0.33 V, at least +0.40 V, at least +0.50 V, atleast +0.60 V, at least +0.67 V, at least +0.75 V, at least +0.80 V, atleast +0.90 V, at least +1.00 V, at least +1.10 V, at least +1.20 V, oreven at least +1.25 V.

Some oxidizing acids are not particularly stable in aqueous solutions.Accordingly, providing a composition with an oxidizing acid prepared invitro can be advantageous. For example, in one preferred embodiment, toa solvent component of a composition can be provided acetic acid andhydrogen peroxide which, when contacted, reversibly form peracetic acid.

The amount of any given acid employed can be determined from the targetpH of a given composition and the pK_(a) value(s) of the chosen acids inview of the type and amounts of compound(s), if any, utilized to achievethe desired effective solute concentration in the composition. (Morediscussion of osmolarity and the types of osmolarity-adjusting compoundsappears below.)

Also present in the solute component of the composition is anelectrolyte oxidizing agent that does not contain any active hydrogenatoms when subjected to a Zerewitinoff determination. Non-limitingexamples of potentially useful electrolyte, preferably inorganic,oxidizing agents include compounds which include anions such asmanganate, permanganate, peroxochromate, chromate, dichromate,peroxymonosulfate, and the like. (Some of these electrolytes can impactpH, so a composition formulated to have a given pH might requireadjustment after addition of the oxidizing agent(s).) Preferred arethose compounds having E⁰ _(red) values of at least +1.25 V, preferablyat least +1.5 V, more preferably at least +1.75 V, even more preferablyat least +2.0 V and most preferably at least +2.25 V.

Electrolyte oxidizing agents generally can be added at up to theirindividual solubility limits, although the maximum amount generally ison the order of 30 g per liter of total composition. Exemplary ranges ofelectrolyte oxidizing agent(s) are ˜2 to ˜25 g/L, ˜3 to ˜21 g/L, ˜4 to˜18 g/L, ˜5 to ˜16 g/L and ˜6 to ˜14 g/L. Exemplary amounts ofelectrolyte oxidizing agent(s) are 17.5±12 g/L, 15±9 g/L, 12.5±6 g/L and10±3 g/L.

Once the acid(s) and oxidizing agent(s) are added to a solvent componentthat contains water (or vice versa), each at least partiallydissociates.

A composition that includes only a solvent component and a solutecomponent that consists, or consists essentially of, one or moreoxidizing acids and one or more electrolyte oxidizing agents can haveefficacy against endospores, i.e., can result in some or all endosporesbeing rendered incapable of returning to a vegetative state.Nevertheless, a composition that includes a solute component whichincludes additional subcomponents can have enhanced efficacy in certaincircumstances.

In certain embodiments, the effective solute concentration of thecomposition can be relatively high. Often, efficacy increases aseffective solute concentration (osmolarity) increases. The presence ofan abundance of solutes ensures that a sufficient amount are present toinduce a high osmotic pressure across the cortical membrane, leading tolysis.

This efficacy is independent of the particular identity or nature ofindividual compounds of the solute component, although smaller moleculesare generally more effective than larger molecules due to solventcapacity (i.e., the ability to (typically) include more small moleculesin a given amount of solvent component than an equimolar amount oflarger molecules) and ease of transport across cortical membranes.

Any of a number of solutes can be used to increase the compositionosmolarity.

One approach to achieving increased osmolarity of the composition is byadding large amounts of non-oxidizing electrolytes, particularly ioniccompounds (salts); see, e.g., U.S. Pat. No. 7,090,882. Like theoxidizing acid and inorganic oxidizing agent, non-oxidizing electrolytesdissociate upon being introduced into a solvent component that includeswater.

Where one or more organic acids are used in the composition, anotherapproach to increasing osmolarity without increasing the pH of thecomposition past a desired target involves inclusion of salt(s) of oneor more the acid(s) or the salt(s) of one or more other organic acids.Such compounds, upon dissociation, increase the effective amount ofsolutes in the composition without greatly impacting the molarconcentration of hydronium ions while, simultaneously, providing abuffer system in the composition.

For example, where the composition includes an acid, a fraction up to amany fold excess (e.g., 3× to 10×, at least 5× or even at least 8×) ofone or more salts of that (or another) acid also can be included. Theidentity of the countercation portion of the salt is not believed to beparticularly critical, with common examples including ammonium ions andalkali metals. Where a polyacid is used, all or fewer than all of the Hatoms of the carboxyl groups can be replaced with cationic atoms orgroups, which can be the same or different. For example, mono-, di- andtrisodium citrate all constitute potentially useful buffer precursors,whether used in conjunction with citric acid or another organic acid.However, because trisodium citrate has three available basic sites, ithas a theoretical buffering capacity up to 50% greater than that ofdisodium citrate (which has two such sites) and up to 200% greater thanthat of sodium citrate (which has only one such site).

Regardless of how achieved, the effective solute concentration of thecomposition is at least 1.0 Osm/L, generally at least 1.25 Osm/L, oftenat least 1.5 Osm/L, commonly at least 1.75 Osm/L, more commonly at least2.0 Osm/L, typically at least 2.25 Osm/L, more typically at least 2.5Osm/L. (As points of comparison, in biological applications, a 0.9% (bywt.) saline solution, which is ˜0.3 Osm/L, typically is considered to behave moderate tonicity, while a 3% (by wt.) saline solution, which is˜0.9 Osm/L, generally is considered to be hypertonic.) In someembodiments, the composition has an effective solute concentration of atleast ˜3.0, at least ˜3.25, at least ˜3.5, at least ˜3.75, or even atleast ˜4.0 Osm/L, with the upper limit being defined by the solubilitylimit of the solutes in the solvent component; in some embodiments, theupper limit of effective solute concentration can range as high as 4.5,4.75, 5.0, 5.25, 5.5, 5.75, 6.0, 6.25, 6.5, 6.75, 7.0, 7.2, 7.4, 7.6,7.8, 8.0, 8.2, 8.4, 8.6, 8.8 or even ˜9 Osm/L. Effective soluteconcentration ranges involving combinations of any of the lower andupper limits set forth in this paragraph also are envisioned. Theeffective solute concentrations of compositions according to the presentinvention, which are intended to be effective against (i.e., lethal to)endospores, generally are higher than those described in U.S. Pat. Nos.8,940,792 and 9,314,017 as well as U.S. Pat. Publ. Nos. 2010/0086576,2013/0272922, 2013/0079407 and 2016/0073628, all of which are directedgenerally against planktonic bacteria and biofilms.

Effective solute concentration can be calculated using known techniquesor, if desired, measured using any of a variety of colligative propertymeasurements such as boiling point elevation, freezing point depression,osmotic pressure and lowering of vapor pressure.

Unlike many of the compositions described in the documents listed in thepreceding paragraph, the present sporicidal composition does not requireinclusion of surfactant in the solute component, although certainpreferred embodiments include one or more wetting agents which include,but are not limited to, surfactants.

Essentially any material having surface active properties in water canbe employed, regardless of whether water is present in the solventcomponent of the composition, although those surface active agents thatbear some type of ionic charge are expected to have enhancedantimicrobial efficacy because such charges, when brought into contactwith a bacteria, are believed to lead to more effective bacterialmembrane disruption and, ultimately, to cell leakage and lysis.

Polar surfactants generally are more efficacious than non-polarsurfactants, with ionic surfactants being most effective. For polarsurfactants, anionic surfactants generally are the most effective,followed by zwitterionic and cationic surfactants, with smallermolecules generally being preferred over larger ones. The size ofside-groups attached to the polar head can influence the efficacy ofionic surfactants, with larger size-groups and more side-groups on thepolar head potentially decreasing the efficacy of surfactants.

Potentially useful anionic surfactants include, but are not limited to,ammonium lauryl sulfate, dioctyl sodium sulfosuccinate,perflourobutanesulfonic acid, perfluorononanoic acid,perfluorooctanesulfonic acid, perfluorooctanoic acid, potassium laurylsulfate, sodium dodecylbenzenesulfonate, sodium laureth sulfate, sodiumlauroyl sarcosinate, sodium myreth sulfate, sodium myreth sulfate,sodium pareth sulfate, sodium stearate, sodium chenodeoxycholate,N-lauroylsarcosine sodium salt, lithium dodecyl sulfate,1-octanesulfonic acid sodium salt, sodium cholate hydrate, sodiumdeoxycholate, sodium dodecyl sulfate (SDS), sodium glycodeoxycholate,sodium lauryl sulfate (SLS), and the alkyl phosphates set forth in U.S.Pat. No. 6,610,314. SLS is a particularly preferred material.

Potentially useful cationic surfactants include, but are not limited to,cetylpyridinium chloride (CPC), cetyl trimethylammonium chloride,benzethonium chloride, 5-bromo-5-nitro-1,3-dioxane,dimethyldioctadecylammonium chloride, cetrimonium bromide,dioctadecyldimethylammonium bromide, tetradecyltrimethyl ammoniumbromide, benzalkonium chloride (BK), hexadecylpyridinium chloridemonohydrate and hexadecyltrimethylammonium bromide.

Potentially useful nonionic surfactants include, but are not limited to,sodium polyoxyethylene glycol dodecyl ether,N-decanoyl-N-methylglucamine, digitonin, n-dodecyl ß-D-maltoside, octylß-D-glucopyranoside, octylphenol ethoxylate, polyoxyethylene (8)isooctyl phenyl ether, polyoxyethylene sorbitan monolaurate, andpolyoxyethylene (20) sorbitan cholamidopropyl)dimethylammonio]-2-hydroxy-1-propane sulfonate, 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate, 3-(decyldimethylammonio)propanesulfonate inner salt, andN-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate.

Potentially useful zwitterionic surfactants include sulfonates (e.g.3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate), sultaines(e.g. cocamidopropyl hydroxysultaine), betaines (e.g. cocamidopropylbetaine), and phosphates (e.g. lecithin).

For other potentially useful materials, the interested reader isdirected to any of a variety of other sources including, for example,U.S. Pat. Nos. 4,107,328, 6,953,772, 7,959,943, and 8,940,792.

The amount(s) of wetting agent(s) to be added to the composition islimited to some extent by the target effective solute concentration andcompatibility with other subcomponents of the solute component of thecomposition. The total amount of wetting agent present in thecomposition can range from at least 0.1%, from at least 0.25%, from atleast 0.5%, from at least 0.75% or from at least 1% up to 5%, commonlyup to 4%, more commonly up to 3%, and typically up to 2.5%. At times,maximum amounts of certain types of wetting agents, particularlysurfactants, that can be present in a composition for a particular enduse (without specific testing, review and approval) are set bygovernmental regulations.

If more than one type of surfactant is employed, the majority preferablyis an ionic surfactant, with the ratio of ionic-to-nonionic surfactantgenerally ranging from ˜2:1 to ˜10:1, commonly from ˜5:2 to ˜15:2, andtypically from ˜3:1 to ˜7:1. Additionally, as is known in the art, acomposition should not include surfactant types that are incompatible,e.g., anionic with cationic or zwitterionic with either anionic orcationic.

The antimicrobial composition can include a variety of additives andadjuvants to make it more amenable for use in a particular end-useapplication with negatively affecting its efficacy in a substantialmanner. Examples include, but are not limited to, emollients,fungicides, fragrances, pigments, dyes, defoamers, foaming agents,flavors, abrasives, bleaching agents, preservatives (e.g., antioxidants)and the like. A comprehensive listing of additives approved by the U.S.Food and Drug Administration is available as a zipped text file athttps://www.fda.gov/media/72482/download (link active as of filing dateof this application).

The composition's efficacy does not require the inclusion of an activeantimicrobial agent (defined above) for efficacy, but such materials canbe included in certain embodiments. Non-limiting examples of potentiallyuseful active antimicrobial additives include C₂-C₈ alcohols (other thanor in addition to any used as an organic liquid of the solventcomponent) such as ethanol, n-propanol, and the like; aldehydes such asgluteraldehyde, formaldehyde, and o-phthalaldehyde;formaldehyde-generating compounds such as noxythiolin, tauroline,hexamine, urea formaldehydes, imidazolone derivatives, and the like;anilides, particularly triclocarban; biguanides such as chlorhexidineand alexidine, as well as polymeric forms such as poly(hexamethylenebiguanide); dicarboximidamides (e.g., substituted or unsubstitutedpropamidine) and their isethionate salts; halogen atom-containing orreleasing compounds such as bleach, ClO₂, dichloroisocyanurate salts,tosylchloramide, iodine (and iodophors), and the like; silver and silvercompounds such as silver acetate, silver sulfadiazine, and silvernitrate; phenols, bisphenols and halophenols (including hexachloropheneand phenoxyphenols such as triclosan); and quaternary ammoniumcompounds.

The following tables provide ingredient lists for exemplary compositionsaccording to the present invention, with amounts being provided in gramsand with distilled water being added to bring the ingredients to avolume of 1 L.

TABLE 4 Formulations for exemplary compositions Formulation 1Formulation 2 salt of organic acid  5-25 10-20 organic acid 125-200140-180 ionic surfactant  5-30 15-25 nonionic surfactant 0-5 1-3 H₂O₂(30% by wt. in H₂O) 175-325 200-300 inorganic oxidizing agent  4-20 6-12 organic liquid 175-450 225-375

Various embodiments of the present invention have been provided by wayof example and not limitation. As evident from the foregoing tables,general preferences regarding features, ranges, numerical limitationsand embodiments are, to the extent feasible and as long as notinterfering or incompatible, envisioned as being capable of beingcombined with other such generally preferred features, ranges, numericallimitations and embodiments.

A composition according to the present invention is intended to be, andin practice is, aggressively antimicrobial. Its intended usages are inconnection with inanimate objects such as, in particular, hard surfaces,particularly those commonly found in healthcare facilities.

The composition can be applied to inanimate objects, particularly hardsurfaces, in a variety of ways including pouring, spraying or misting,via a distribution device (e.g., mop, rag, brush, textile wipe, etc.),and the like.

Alternatively, certain objects are amenable to being immersed in acomposition. This is particularly true of medical equipment designed foruse with multiple patients such as, for example, dialysis equipment, anyof a variety of endoscopes, duodenoscopes, etc., endoscopic accessoriessuch as graspers, scissors and the like, manual instruments such asclamps and forceps, laparoscopic surgical accessories, orthopedic andspinal surgery hardware such as clamps and jigs, and the like. Becausethe composition of the present invention has a more moderate [H⁺] thantreatments such as peracetic acid and bleach, it can achievedisinfection, high level disinfection or even sterilization withoutnegative effects such as, e.g., polymeric degradation, metal corrosion,glass or plastic etching, and the like.

Once applied to a surface or object, the various ingredients of thecomposition act on any endospores present and avoid or break down theirvarious defenses. The contact time necessary for a composition to treatendospores (i.e., ensure that they cannot return to a vegetative state)can vary widely depending on the particular composition and its intendedend use.

For example, embodiments of a composition intended to be applied to hardsurfaces in a healthcare facility can achieve at least a 3.0, 3.2, 3.4,3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8 or 5.0 log reduction after a contacttime of more than 1200 seconds, no more than 1050 seconds, no more than900 seconds, no more than 840 seconds, no more than 780 seconds, no morethan 720 seconds, no more than 660 seconds, or even no more than 600seconds. When tested in accordance with ASTM E2197-11, certainembodiments can achieve at least a 4.5 log reduction after a contacttime of 600 seconds.

These and/or other embodiments of a composition intended for use as asoaking bath for medical devices can achieve at least a 5.0, 5.1, 5.2,5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, or 6.0 log reduction after a contacttime of ˜14,400 seconds, up to ˜10,800 seconds, up to ˜7200 seconds, upto ˜5400 seconds, and on the order of ˜3600 seconds. When tested inaccordance with AOAC Official Method 966.04, certain embodiments canachieve a passing score after contact times as low as 1800 seconds.

Embodiments of the sporicidal composition may be able to be classifiedas high level disinfectants or even as sterilants.

After the composition has been allowed to contact a given object orsurface for an appropriate time (in view of factors such as expectedbacterial load, type of bacteria potentially present, importance of theobject/surface, etc.), it can be left to evaporate or, preferably,rinsed away with water or a dilute saline solution.

The following non-limiting, illustrative examples provide detailedconditions and materials that can be useful in the practice of thepresent invention. Throughout those examples, any reference to roomtemperature refers to ˜22° C.

EXAMPLES Example 1 (Comparative) Peracetic Acid

A widely recognized and recommended disinfection treatment whereendospores are possible or suspected is application to the targetsurface and 10 minute contact time of 10% (w/v) peracetic acid.Accordingly, peracetic acid constitutes a good comparative forcompositions of the present invention.

Two peracetic acid solutions were prepared by adding distilled water toa flask containing peracetic acid. The concentration of one of thesolutions was 5% (w/v) while that of the other was 10% (w/v). Thecalculated effective solute concentrations for these solutions were 1.97and 3.95 Osm/L, respectively.

To a 50 mL beaker was added 20 mL distilled water. A cleaned, rinsed anddried probe from a calibrated, temperature compensating pH meter waslowered into the beaker. Sequential aliquots of the peracetic acidsolution then were added to the beaker, with pH readings after each. Thetitrations were performed at room temperature.

The results of these titrations are shown below in Table 5.

TABLE 5 Peracetic acid titrations 5% (w/v) 10% (w/v) Amt. acid, Amt.acid, mL pH mL pH 0 5.91 0 5.31 0.25 2.42 0.1 2.74 0.50 2.17 0.2 2.480.75 2.00 0.3 2.33 1.00 1.89 0.4 2.22 1.25 1.80 0.5 2.14 1.50 1.74 0.62.07 1.75 1.68 0.7 2.00 2.00 1.59 0.8 1.95 2.25 1.56 0.9 1.91 2.50 1.531.0 1.86 2.75 1.48 1.1 1.83 3.00 1.45 1.2 1.79 3.25 1.42 1.3 1.76 3.501.41 1.4 1.73 3.75 1.38 1.5 1.70 4.00 1.34 1.6 1.67 4.25 1.30 1.7 1.654.50 1.28 1.8 1.62 4.75 1.26 1.9 1.60 5.00 1.25 2.0 1.58

The above data indicate, inter alia, that the pH of water is reduced tobelow 3 upon addition of even a tiny aliquot, i.e., less than 1% byvolume, of either peracetic acid solution and that the addition of only1 mL (5% by volume) of either solution has reduced the pH to below 2.Further, the asymptotic pH for either acid solution is on the order of1.1±0.1.

Further, U.S. EPA recommendations are for peracetic acid solutions of atleast 2.5% (w/v) which, according to the tabulated data, has a pH of nomore than 1.25.

Thus, any worker performing this recommended disinfection procedure(i.e., application of a 2.5-10% peracetic acid solution) should employthe types of precautions appropriate for handling strong acids such as,e.g., protective gloves, protective eyewear, breathing masks, etc.

Example 2 (Comparative) Bleach

Another widely recognized and recommended disinfection treatment whereendospores are possible or suspected is application to the targetsurface and 10 minute contact time of a bleach solution.

To a 50 mL beaker was added 5 mL of a bleach solution, i.e., 8.25% (w/v)sodium hypochlorite. A cleaned, rinsed and dried probe from acalibrated, temperature compensating pH meter was lowered into thebeaker. Sequential aliquots of distilled water then were added to thebeaker, with pH readings after each.

The data from this titration are shown below in Table 6.

TABLE 6 Titration of household bleach with water Water, [ClO⁻], % mL(w/v) pH 0 8.25 12.56 2 5.89 12.46 4 4.58 12.33 6 3.75 12.23 8 3.1712.14 10 2.75 12.06 12 2.43 12.00 14 2.17 11.94 16 1.96 11.89 18 1.7911.84 20 1.65 11.79 22 1.53 11.74 24 1.42 11.70 25 1.38 11.68

The data of this table indicate, inter alfa, that an undiluted 8.25%bleach solution has a pH of almost 13 and that reducing the ClO⁻concentration by three-fourths reduces this only to ˜11.9. Conversely,reducing the concentration from 8.25% to 5% (both w/v) results in thecalculated effective solute concentration being reduced by almost half,i.e., from 2.28 to 1.34 Osm/L.

Thus, any worker performing this recommended disinfection procedure(i.e., application of a bleach solution) should employ the types ofprecautions appropriate for handling strong bases, e.g., protectivegloves, protective eyewear, breathing masks, etc.

Examples 3-10 In Vitro Time-to-Kill

Efficacy of certain sporicidal compositions was performed againstClostridium difficile (ATCC #43598). In this testing, reduction ofbacteria is determined by comparison against untreated controls(employing phosphate buffered saline as liquid) at various time testpoints, typically equal increments such as 15 minutes (900 seconds).

A 9.9 mL aliquot of the solution to be tested was placed in a 20 mL testtube. A 0.1 mL volume of the test culture (˜10⁶ colony forming units(CFU) of C. Diff per mL when diluted) was added to the test tube, whichthen was vortexed. After a predetermined amount of contact time, 1.0 mLof the sample/test culture suspension was transferred into sterile testtubes containing 9.0 mL of an appropriate neutralization solution,followed by additional vortexing.

Serial tenfold dilutions then were prepared by transferring 0.5 mLaliquots of test solution into 4.5 mL of neutralizing solution, withvortex mixing between dilutions. From these dilutions, duplicate 1.0 mLaliquots were spread-plated onto brain-heart agar plates, which thenwere incubated anaerobically at 35°±2° C. for ˜72 hours.

Following incubation, the colonies on the plates were counted, withcounts in the 20 to 200 CFU range used in data calculations. The logreduction from this testing is performed by subtracting the CFU/mLrecovered treatment value from the CFU/mL recovered control sample.

A number of compositions were tested in this manner, with the time toachieve 6 log reductions in spores shown in the last column of Table 7below. Each of the compositions was prepared based on a targeted ˜2.3Osm/L effective solute concentration and a target pH of 4. (In thebuffer system column, “A” represents acetic acid/sodium acetate, while“C” represents citric acid/trisodium citrate. In the oxidant column,“PPOMS” represents peroxymonosulfate, all at 0.22% (w/v), and “PAA”represents peracetic acid at the noted concentration.) Thosecompositions designated as employing BK as a surfactant included 0.21%(w/v), while those designated as employing SDS included 0.175% (w/v).For those compositions showing inclusion of an organic liquid, anisopropanol solution (70% in water) was employed.

TABLE 7 Buffer Org. liquid Time Example system Oxidant Surfactant (%,w/v) (min.) 3 A PPOMS BK — 30 4 A PPOMS SDS — 30 5 A PPOMS BK 10.0 60 6C PAA (0.1%) BK 20.0 30 7 C PAA (1.0%) BK 20.0 30 8 A PPOMS BK — 30 9 APPOMS SDS — 30 10 A PPOMS SDS 10.0 15

The times shown in the foregoing table are better than those which canbe achieved with most commercially available sporicidal products, whichtypically require 240 to 2160 minutes for C. Diff disinfection.Additionally, exposure to each of these compositions is far lessdangerous than exposure to such commercial products.

Examples 11-22

The data from Table 7 above seem to indicate that compositions employingan anionic surfactant (SDS) might provide better results than thoseemploying a cationic surfactant (BK).

To further investigate efficacy, additional compositions were prepared,each of which employed the same amount of SDS as was used in Examples 4and 9-10 plus 0.02% (w/v) of a polysorbate-type nonionic surfactant.Each also included 250 g/L of a 30% H₂O₂ solution and 300 g/L of anorganic liquid. The electrolyte oxidizing agent (EOA) for eachcomposition was PPOMS. The citric acid-containing compositions included140 g/L citric acid and 17.5 g/L trisodium citrate dihydrate (along withthe noted amounts of NaCl to raise the effective solute concentration toa predetermined target), while the acetic acid-containing compositionsincluded the noted amounts of acetic acid (AA) and sodium acetate (SA).

Quantitative carrier testing was performed in substantial accord withASTM standard E2197-11, with efficacy against spores being shown in thelast columns of the following tables.

TABLE 8a citric acid compositions Target Amt. NaCl Amt. EOA Organic LogExample pH (g/L) (g/L) liquid reduction 11 1.5 54.0 12.0 IPA 5.6 12 3.554.0 4.0 IPA 3.2 13 1.5 178.2 12.0 DGME <3 14 3.5 178.2 4.0 DGME <3 152.5 116.0 8.0 DGME 3.9 16 2.5 116.0 8.0 IPA 3.9

TABLE 8b acetic acid compositions Target Amts. AA/SA Amt. EOA OrganicLog Example pH (g/L) (g/L) liquid reduction 17 1.5 82.4/7.4 4.0 DGME 5.018 3.5 82.4/7.4 12.0 DGME 3.3 19 1.5 164.9/14.8 4.0 IPA 5.1 20 3.5164.9/14.8 12.0 IPA 4.7 21 2.5 123.6/11.1 8.0 DGME 5.3 22 2.5 123.6/11.18.0 IPA 5.0

Statistical analysis of the data from these tables suggested that thetype of acid has the greatest impact on efficacy followed by, in order,the pH (lower being better), type of solvent, and effective soluteconcentration. The amount of electrolyte oxidizing agent appears to havea lesser effect.

Examples 23-31

Using Example 22 as a center point (rerun below as Example 23),additional quantitative carrier tests were conducted on another round ofprepared compositions in which the targeted pH (2.5), effective soluteconcentration (˜6.4 Osm/L) and amount of PPOMS (8 g/L) were heldconstant. The anionic surfactant was SDS, while the nonionic surfactantwas a polysorbate. The organic liquid for each was a 70% (v/v) IPAsolution.

TABLE 9 Org. liquid H₂O₂ soln. Anionic surf. Nonionic surf. Log Example(g/L) (g/L) (g/L) (g/L) reduction 23 250 250 17.5 2.0 4.6 24 200 20015.0 1.5 4.6 25 400 300 15.0 1.5 4.7 26 200 300 20.0 1.5 4.6 27 400 20020.0 1.5 4.6 28 200 300 15.0 2.5 4.7 29 400 200 15.0 2.5 4.6 30 200 20020.0 2.5 4.5 31 400 300 20.0 2.5 4.7

Analysis of the data for Examples 11-31 indicated that pH and type ofacid had the greatest impact, followed by effective solute concentrationand type of solvent.

Examples 32-40

Additional quantitative carrier testing was performed on compositions inwhich the pH (2.5) and effective solute concentration (˜6.4 Osm/L) wereheld constant. This set varied the amount of electrolyte oxidizing agent(PPOMS), the amount and type of solvent (with E representing absoluteethanol), the amount of hydrogen peroxide solution, and the amounts ofanionic (SDS) and nonionic (polysorbate-type) surfactants.

TABLE 10 Org. H₂O₂ Anionic Nonionic Log liquid soln. PPOMS surf. surf.reduc- Example (g/L) (g/L) (g/L) (g/L) (g/L) tion 32 E, 250 200 12 15.01.5 4.7 33 E, 250 300 20 15.0 1.5 4.7 34 DGME, 250 300 12 20.0 1.5 4.535 DGME, 250 200 20 20.0 1.5 3.9 36 E, 350 300 12 15.0 2.5 3.8 37 E, 350200 20 15.0 2.5 4.5 38 DGME, 350 200 12 20.0 2.5 4.6 39 DGME, 350 300 2020.0 2.5 4.7 40 IPA, 300 250 16 17.5 2.0 4.7

Analysis of this data suggests that, when type and amount of acid isheld constant, the most statistically significant factors might betwo-way combinations type of solvent, solvent concentration, and amountof electrolyte oxidizing agent.

That which is claimed is:
 1. A sporicidal composition having a pH offrom 1.65 to 3.75, inclusive, and a calculated effective soluteconcentration of at least 3 Osm/L, said composition comprising, on a perliter basis: a) a solvent component having a δ_(p) value no more than15.2 MPa^(1/2) that comprises 1) 50 to 500 mL water and 2) from 175 to450 g of at least one organic liquid, and b) a solute component thatcomprises 1) dissociation products of an oxidizing acid having a pK_(a)value of greater than 3 and a standard potential of at least +0.5 V, 2)dissociation products of from 4 to 20 g of an electrolyte oxidizingagent having a standard potential of at least +1.5 V, and 3)dissociation products of at least one salt of an organic acid.
 2. Thesporicidal composition of claim 1 wherein said solute component furthercomprises wetting agent.
 3. The sporicidal composition of claim 2wherein said wetting agent comprises anionic surfactant.
 4. Thesporicidal composition of claim 3 wherein said wetting agent furthercomprises nonionic surfactant.
 5. The sporicidal composition of claim 4wherein said solute component comprises dissociation products of 12.5±6g of said electrolyte oxidizing agent.
 6. The sporicidal composition ofclaim 4 wherein said electrolyte oxidizing agent has a standardpotential of at least +2.0 V.
 7. The sporicidal composition of claim 6wherein said solute component comprises dissociation products of 12.5±6g of said electrolyte oxidizing agent.
 8. The sporicidal composition ofclaim 1 wherein said oxidizing acid is the reaction product of anorganic acid and a peroxide.
 9. The sporicidal composition of claim 1having a pH of no more than
 3. 10. The sporicidal composition of claim 1wherein said electrolyte oxidizing agent has a standard potential of atleast +2.0 V.
 11. The sporicidal composition of claim 10 wherein saidsolute component comprises 12.5±6 g of said electrolyte oxidizing agent.12. The sporicidal composition of claim 1 having a pH of no more than 3.13. The sporicidal composition of claim 1 wherein said at least oneorganic liquid comprises a glycol ether.
 14. The sporicidal compositionof claim 1 wherein said at least one organic liquid is a glycol ether.15. The sporicidal composition of claim 1 wherein said solvent componenthas a δ_(p) value of from 13.5 to 15.5 MPa^(1/2).
 16. A sporicidalcomposition having a pH of from 1.65 to 3.75, inclusive, and acalculated effective solute concentration of at least 3 Osm/L, saidcomposition comprising, on a per liter basis: a) a solvent componenthaving a δ_(p) value no more than 15.2 MPa^(1/2)that comprises 1) 50 to500 mL water and 2) from 175 to 450 g of at least one organic liquidthat comprises a glycol ether, and b) a solute component thatcomprises 1) dissociation products of an oxidizing acid having a pK_(a)value of greater than 3 and a standard potential of at least +0.5 V, 2)dissociation products of from 12.5±6 g of an electrolyte oxidizing agenthaving a standard potential of at least +1.5 V, 3) dissociation productsof at least one salt of an organic acid, and 4) wetting agent.
 17. Thesporicidal composition of claim 16 wherein said solvent component has aδ_(p) value of from 13.5 to 15.5 MPa^(1/2).
 18. The sporicidalcomposition of claim 16 wherein said at least one organic liquid is aglycol ether.
 19. The sporicidal composition of claim 16 wherein saidwetting agent comprises anionic surfactant and optionally a nonionicsurfactant.
 20. The sporicidal composition of claim 16 wherein saidelectrolyte oxidizing agent has a standard potential of at least +2.0 V.